Spring device for rolling up a roller curtain

ABSTRACT

Elastic means for rolling up a roller curtain include a plurality of springs (26,27,28) fastened rigidly to a common support (15) connected to a shaft (2) and with respective support and constraint elements (36,37,38) which are geometrically coupled to the roller (19). A device for connecting the springs to a stationary frame (35) of the curtain (20) reduces the number of springs torsional turns with respect to the number of turns of the roller (19) by interposition of a speed reducer between the shaft (2), to which the springs are fastened, the stationary frame (35) and the roller (19). The shaft (2) end is located closer to the most external support and constraint element (36) and its extremity has a disc (11) mounted thereto. The coupling device together with the springs (50), their supports (15,36,37,38), the shaft (2) and an external support cylindrical body (6) form a compact assembly, which is introduced into one head of the roller (19). The other head of the roller (19) features a cap (12), rotatably fastened to a cylindrical section of a support (13) which is locked to the stationary frame (35) by a tang (14). The geometrical coupling between the shaft (2) and the spring supports (15,36,37,38) allows for easy and quick relocation of the roll up device on each side of the window to which the roller curtain is to be mounted.

BACKGROUND OF THE INVENTION

The present invention relates to production of roller curtains or thelike, which are applied to windows for darkening, for preventing insectsfrom entrance, and the like.

In particular, the present invention concerns configuration of thecurtain rolling up elastic means, their supports, and the connectionsystem between the roller support shaft and the rolling up elasticmeans.

DESCRIPTION OF THE PRIOR ART

These curtains, commonly called roller or roll up curtains, are usuallywound on a roller, which is rotatably supported, in horizontal position,inside a box-like casing situated in the region of the window innerupper edge.

The roller can rotate axially for curtain unrolling and subsequentrolling up.

Amongst all the types of roller curtains, there are two groups of themdistinguished according to the unrolling and rolling mechanism type. Oneof these types includes elastic means, usually a helical spring situatedinside the winding roller and fastened thereto, so that unrollingrotation determines its torsion and consequent elastic reaction can beused later for rolling up the curtain.

The curtain is unrolled by directly pulling it downwards and thensuitable locking means keep it in the desired position until it is to berolled up.

Another type of curtain does not include elastic means and is operatedmanually also for rolling it up.

A small pulley is fastened to the roller head and has a suitably shapedgroove into which an operating chain fits for unrolling and rolling upthe curtain.

In the first type of curtain, one end of the elastic means is rigidlyfastened to the roller while the other end is fixed to the window frame,so that the elastic means are stressed in relation to the curtainunrolling.

According to known techniques, in order to avoid spring undulation, oneof its extremities is fastened to a longitudinally moving elementsituated inside the roller, which rotates along with the roller.

Nevertheless, it is obvious that in case of curtains of a certainlength, reaching the end of the unrolling stroke will require a highnumber of turns of the roller, and spring elastic reaction and torsionalstress will be considerable.

This fact provokes problem in dimensioning of the springs to be usedwhich anyway do not return an elastic reaction that fits the necessarystrength for rolling up the curtain in a uniform way.

Moreover, the supports of the rolling up spring must be adequate for theelastic reaction to be determined and this increases the dimension ofthe supports and the global cost of the curtain production.

Furthermore, montage of the rolling up assembly is complicated, sincethe assembly includes the coupling element between the roller and oneextremity of the rolling up spring, the spring, and a shaft which passesthrough the whole roller and fastens the other extremity of the springto the casing containing the curtain.

All these elements must be assembled inside the roller and adapted toits transversal dimension, which corresponds to the curtain width.

Therefore, the spring tension problem becomes important when a long andnarrow curtain must be unrolled and rolled up, because the length of thespring will not be adequate and thus it will be excessively stressed.

In case of curtains operated completely manually, called also frictioncurtains, the lack of the elastic reaction determines the necessity ofconsiderable strength for rolling the curtain up, a strength whichincreases in relation to the length of the curtain unrolled.

To cope with this problem, the diameter of the driving pulley must belarge to allow curtain rolling up and unrolling with a reduced effort,also for reducing the size of the operating chain. However, the supportdimensions must be determined on the basis of the torque which iscreated in the regions of the ends of the roller. This has effect on theglobal dimension of the casing containing the curtain.

Another problem encountered with the conventional friction curtaindevices is that the unrolling and rolling up device must have thepossibility of being positioned either on one side or on the other sideof the window frame to which the curtain is mounted, in accordance withthe features of the environment where the curtain is mounted.

To obtain this result two possible ways can be followed in the priorart. According to a first way both the components of the rolling upsystem and the components of either one or the other series are used inaccordance with the necessity.

According to the second way only the rolling up spring are produced intwo diverse series, having the same elastic constant but winding inopposite directions.

As it can be easily understood, this fact determines a considerableproblem, and production of the roller curtains in both the ways as wellas distribution and storing thereof cause high costs. Also maintenanceoperation of the curtains produced in both the ways just described iscomplicated and expensive.

The paten specification GB 222,936 to J. Hartley and G. R. Thornborough,disclosed improved means for securing and mounting spiral springs usedin revolving shutters and the like. To afford more power for rising orlowering the shutter, the improved means include cylindrical cores orblocks made in two (or more) diameters and each diameter is spirallygrooved so as to receive a respective spring.

This allows to mount two (or more) springs to roll up the shutter, andthe springs are connected to the roller at one side, by means of a core,and to the internal shaft at the other side, by means of a block.

The object of the present invention is to propose improved elasticmeans, which return elastic reaction in a more gradual way andadequately to the effective force necessary to roll up the curtain as itis unrolled from the roller.

Another object of the present invention is to propose elastic means oflimited dimensions so as to form an assembly which can be rapidly andeasily introduced inside the roller independently from the length of theroller. This is obtained by means of a suitable coupling device, whichnot only locks one extremity of the elastic means to the roller so as toload them elastically, but also reduces the torsion entity, to whichthey are subjected as the roller is rotated.

The previously mentioned features not only improve the curtain working,but also reduce the global production cost.

Another object of the present invention is to improve the connectionmeans which join the elastic means to the roller and to the rollersupporting shaft in a way such that mirror-like relocation of the rollup device, on each side of the window to which the roller curtain is tobe mounted, becomes easy and quick, without any need of replacement ordouble set production.

SUMMARY OF THE INVENTION

These objects are obtained by use of the elastic means for automaticallyrolling up a roller curtain, or respectively for compensating for theweight of friction curtains during manual rolling up thereof, with theroller rotatably supported in horizontal position by a stationary frame,wherein the elastic means include a plurality of helical springs, whichat one extremity are rigidly fastened to a common support connected tosaid shaft, and with the other extremity of each helical spring fastenedto a respective support and constraint element, geometrically coupled tothe roller.

The common support is formed by a step tapered cylinder defining steppedsections, with each spring press-fitted to a corresponding section.

Each support and constraint element includes a cylinder, to which aspring is fastened, a raised edge which engages geometrically with theinternal surface of the roller, and a cavity made axially in thecylinder, into which a spring of a smaller diameter enters.

The shaft is connected with the stationary frame by interposition of aspeed reducer which determines a torsion entity of the elastic meansreduced with respect to the actual rotation of the roller.

The speed reducer, together with the group of springs, their supports,the shaft and the external support cylinder body form a compactassembly, which is introduced into the roller.

Geometrical connection between the shaft and the common spring supportis obtained by means of connection-driving means including splines madeon the shaft and matching a splined hole made in the support so that theshaft can slide therein thus allowing removal and relocation thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristic features of the invention will be pointed out in thefollowing description, with particular reference to the encloseddrawings, in which:

FIG. 1 shows an exploded view of a curtain rolling up system, accordingto the present invention;

FIG. 2 shows a section view of a head of the roller with joined theretoa coupling mechanism described in the following;

FIGS. 3 and 4 show two section views taken along planes III--III andIV--IV of FIG. 2;

FIG. 5 shows a section view of two non contiguous parts of the rollerequipped with rolling elastic means being the subject of the presentinvention;

FIGS. 6 and 7 show transversal section views of the roller taken alongplanes VI--VI and VII--VII of FIG. 5;

FIG. 8 shows a section view of a head of the roller, with joined theretothe elastic means coupling mechanism of a friction curtain;

FIGS. 9 and 10 show two section views taken along planes IX--IX and X--Xof FIG. 2.

BEST MODES OF CARRYING OUT THE INVENTION

The rolling up elastic means, described in the following, can be usedwith both types of curtains, either rolling up with a rolling up springor friction curtains. In the latter case, the elastic means compensatefor the curtain weight.

Nevertheless, to simplify the description, the reference will be made tothe rolling up curtain using a rolling up spring.

With reference to FIGS. 1, 5, 6 and 7, the roller 19, on which thecurtain 20 is rolled up, is rotatably supported in horizontal position,by a stationary element 35, to which one extremity of the elastic meansis connected by a shaft 2, extending inside the roller, via a couplingreducer device 30, described in the following.

The other extremity of the elastic means 50 is fastened directly to theroller 19 and is rotated along with the roller, as described below.

The elastic means 50 include a plurality of helical springs 26, 27, 28,e.g. three. Obviously, the number of springs can be any, within therange imposed by the dimensions of the roller 19 and the size of thesprings to be used.

In the region of a common end, the springs 26, 27, 28 are rigidlyfastened to a common support 15 connected to the shaft 2. Geometricalconnection between the shaft 2 and the common spring support 15 isobtained by means of connection-driving means including splines made onthe shaft and matching a splined hole made in the support 15 which canthus slide along the shaft.

With reference to FIG. 5, the common support 15 includes a step-taperedcylinder forming stepped sections 16, 17, 18. Each spring is press-fitto a corresponding section.

The other extremities of the helical springs 26, 27, 28 are fastened torespective support and restraint elements 36, 37, 38 introduced insidethe roller 19 in geometrical coupling therewith.

Each of the support and restraint elements 36, 37, 38 includes acylinder, on which a respective spring is fastened, a raised edge 46,47, 48 which engages geometrically with the internal surface 19a of theroller 19 and of a cavity 38a, 37a made axially in the respectivecylinder 38, 37 so as to allow the passage of a spring of a smallerdiameter.

These elastic means allow to use springs of different dimensions anddifferent elastic constants instead of the single spring used intraditional roller curtains.

Therefore, it is possible to determine selectively the entity of elasticreaction of each spring, thus adjusting the elastic reaction of thegroup of springs more precisely.

An elastic reaction is thus obtained which is softer and set moregradually during the curtain unrolling.

With separate support elements for each spring, it is possible to mountsprings very different in length, or pre-load, e.g. one or more springsin opposite direction with respect to the others, thus determining theiroperation only from a predetermined point of the curtain unrolling on.

This result can be improved if the shaft 2 is fastened to reducer 30which is connected to the stationary element 35 and to the roller 19.

The resulting advantage is that the elastic reaction of the springs iskept within a more limited range of values thus corresponding moreprecisely to the unrolled curtain weight gradually increasing as thecurtain unrolls.

With reference to figures from 1 to 7, the device 30 includes a cupelement 1, partially introduced into a head of the roller 19, so thatits cavity is turned outside.

The external surface 1a of the cup element 1 matches the internalsurface 19a of the roller 19, as appears evident from FIG. 3, so thatrotation of the roller determines also rotation of the cup element 1.

The cavity 1b of the cup element 1 features an internal ring gear 21 andhas a concentric through hole made in its bottom, through which theshaft 2 passes freely.

The device includes also a plurality of planetary gears 3, supported, soas to engage the ring gear 21, by a spider member, or planet carrier, 5with a concentric hole 5a, inside which the extremity of the shaft 2,opposite to the one fastened to the elastic means 50, is introduced withgeometrical coupling.

The shaft is blocked inside the hole by fixing screw means of knowntype, or by glue.

The planet carrier 5 is combined with a perforated plate 4 that keepsthe planetary gears 3 in their positions on respective support pins.

Finally, the roller is supported externally by a cylindrical body 6,fastened in a firm position to the stationary element 35 by ageometrical coupling with its shank 8.

The cylindrical body 6 is inserted into the cavity 1b of the cup element1, with possibility of reciprocal rotation, and features a toothedprotrusion 7 extending axially, which is introduced between theplanetary gears 3, thus forming the sun gear of the planetary gear trainincluding, beside the toothed protrusion 7, the planetary gears 3 andthe internal ring gear 21, as is well seen in FIG. 3.

The so far described elements are housed in the cup 1 which isintroduced in the head of the roller 19.

FIGS. 8, 9 and 10 show the same device mounted to a friction curtain,which is unrolled and rolled up by a chain 22, fitting into a shapedgroove of a small pulley 9 made on the most external edge of the cupelement 1.

Operation of the device will be described in the following.

When the curtain is unrolled from the roller by the direct action of astring which is pulled in the direction T, see FIG. 4 for the automaticrolling up curtain, or by pulling a chain 22 mounted on the pulley 9 ofthe cup element 1, rotation of the roller 19 determines the torsion ofthe extremity of the elastic means 50 fastened thereto, but at the sametime, it rotates also the cup element 1, so that the ring gear 21determines rotation of the planetary gears 3 with respect to a sun wheelformed by the toothed protrusion 7.

Consequently, the planet carrier 5 is rotated with angular displacementsreduced with respect to those of the roller 19.

The planet carrier transmits the rotation movement to the shaft 2, whichacts on the springs 26, 27, 28 via the common support 15 with reducedentity with respect to the rotation of the roller 19, that acts directlyon the support and constraint elements 36, 37, 38.

Since the rotation directions of these members are the same, the elasticmeans 50 will be subjected to a reduced torsional stress, thatcorresponds to the difference in angular displacements, i.e. correspondsto the reduction rate imposed by the coupling device 30.

All this allows to use the same torsional entity of the elastic means 50along an unrolling path more extended than with the conventional curtainroll up devices.

This means that normal length curtains equipped with the subject devicewill require a torsional stress reduced with respect to curtainsequipped with conventional roll up devices.

The shaft 2 has a size such that its end remains near the most externalsupport and constraint element, and in this point it is provided with acoaxial disc 11 or another element of almost cylindrical section, whichkeeps the shaft 2 concentric with respect to the roller 19.

A considerable advantage deriving from use of the group of springs 50co-operating with the elastic means coupling device 30 lies in thepossibility to reduce the springs length.

This, together with the fact that the shaft 2 does not pass through thewhole roller as in traditional curtains, allows to dramatically reducethe length of the whole group and make it independent from the roller 19length.

In fact, the coupling device 30 together with the elastic means 50 andthe shaft 2 form a compact and small group, which is introduced in theregion of a head of any winding roller, independently from its length.

The other head of the roller 19 accommodates a cap 12, rotatably mountedto a cylindrical support 13, featuring a tang 14, similar to the shankof the cylindrical body 6, engaging with a corresponding receiving seatsuitably made in the stationary frame for supporting the roller 19.

The cap 12 carries means for reversible locking of the curtain in anyposition which it must assume and maintain when it is un rolled.

This allows to use the same rolling up mechanism for curtains androllers of different width, giving the components bigger versatility.

Obviously, the compact form of the rolling up system allows it to beapplied also to friction curtains, operated manually also for rolling upthe curtain by means of a chain 22 (FIG. 10), acting in this case onlyas compensation for the curtain weight which increases as the curtain isunrolled from the roller 19.

The rolling up system of the present invention allows easy and quickmirror-like relocation of the roll up device, on each side of the windowto which the roller curtain is to be mounted. To re-locate the rollingup device the following operations must be carried out.

Firstly, the coupling reducer device 30 is removed from the shaft 2 sothat the spider member 5 is set free and taken away from the shaft 2.Also the pulley 9 is removed from the shaft. Then, the shaft 2 iswithdrawn from the elastic means 50 with a simple sliding movement, sothat the shaft end 2a comes out beside the roller coupled supportcylinders 36,37,38.

The shaft 2 is inserted again with the end 2a into the elastic means 50on the opposite side, i.e. into the common support 15. Lastly, thepulley 9 and the spider support 5 can be mounted again onto the shaft 2,in the region of the end 2a, that has taken the place of the end 2b ofthe shaft 2, which carries the coaxial disc 11.

Therefore, another advantage of the present invention is that infriction curtains the roll up system can be indifferently located eitheron the left or on the right side of the curtain casing by simplerelocation thereof, without necessity of production of doubled setassemblies which are to be chosen upon montage.

Also storing room of the necessary components is reduced since the sameassembly can be mounted with the roll up system on one side or on theother side.

It is understood that the subject invention has been described, withreference to the enclosed drawings, as a mere, not limitative example,therefore possible variants resulting from practice and use areprotected by the present invention as described above and claimedhereinafter.

What is claimed is:
 1. A device for rolling up a curtain comprising:aroller rotatably supported in a horizontal position by a stationaryframe, the roller having a shaft, a common support connected to theshaft through a geometrical engagement, elastic means including aplurality of helical springs, each having a first extremity rigidlyfastened to the common support, and each having a second extremityfastened to a respective support and constraint element each coupled ina shape mating manner to the roller, said common support being a steptapered cylinder defining stepped sections, each helical springpress-fitted to a corresponding section, each support and constraintelement having a cylinder to which the respective second helical springextremities are fastened, a raised edge engaged geometrically with aninternal surface of the roller, and each support and constraint cylinderhaving a cavity made axially therethrough.
 2. The device according toclaim 1, further comprising a speed reducer connected between the shaftand the stationary frame, the speed reducer reducing torsional stresswith respect to the rotation of the roller.
 3. The device according toclaim 2, wherein a compact assembly for combination with the rollercomprises the speed reducer assembled with the elastic means, the commonsupport, the support and constraint elements, the shaft and an externalsupport cylindrical body, the compact assembly having a length which isindependent of the length of the roller.
 4. The device according toclaim 3, wherein the speed reducer has a cup element introduced at leastpartly into a head of the roller, the cup element having a cavity facingoutwardly relative to the roller, the cup element geometrically coupledwith the roller, an internal ring gear located inside the cavity, thecup element having a through hole for receiving the shaft therein, aplurality of planetary gears supported on a planet carrier, and engagedto the ring gear, the planet carrier having a concentric hole whichreceives an end of the shaft therein, the shaft being geometricalcoupled thereto, the external support cylindrical body fastened rigidlyto the stationary frame, and having a toothed protrusion extendingaxially between the planetary gears for engagement therewith to form asun wheel of a planetary gear train.
 5. The device according to claim 2,further comprising a co-axial disk, rotatably fastened to the shaft forkeeping the shaft concentric with respect to the roller.
 6. The deviceaccording to claim 1, wherein the geometrical engagement between theshaft and the common support comprises splines made on the shaft engagedto a hole having mating splines made in the support so that the shaftcan slide therein to allow removal and relocation thereof.